1,3,5-tris(isopropenyl) benzene



Patented Feb. 20, 1951 1,3,5-TRIS (ISOPROPENYL) BENZENE Charles H. McKeever, Glenside, and John 0. Van

Hook, Roslyn, Company, Delaware Pa., assignors to Rohm & Haas Philadelphia, Pa., a corporation of No Drawing. Application November 10, 1949, Serial No. 126,676

4 Claims. (01. 260-6735) This invention deals with tris(isopropenyl)- benzene and with methods for its preparation.

The reaction of acetone and acetylene in the presence of potassium hydroxide in the presence of oxygenated solvents is known to yield 3- methyl-1-butyn3-ol. When this triple-bonded alcohol is heated in the presence of acidic catalysts, as is known, there is readily obtained isopropenylacetylene, CH2=C(CH3)CECH, or 2-me1hyl-1-buten-3-yne.

We have now found that tris(isopropenyl)- benzene is formed by trimerizing 3-methyl-1- butyn-3-ol to form tris(l-methyl-1-hydroxyethyhbenzene and dehydrating this product. Alternatively, tris(isopropenyl)benzene is formed by dehydrating 3-methyl-1-butyn-3-ol to isopropenylacetylene and trimerizing the latter.

Trimerizing is accomplished by heating the methylbutynol or isopropenylacetylene in the presence of a nickel carbonyl-substituted phosphine catalyst at to 120 C. The trimerization is preferably accomplished in an inert, organic solvent, such as benzene, toluene, xylene, petroleum ether, naphha, or the like.

The perferred catalysts are nickel carbonyltriphenyl phosphine combinations in which one to two moles of triphenyl phosphine are reacted with one mole of nickel carbonyl. To prepare the catalyst a solution of nickel carbonyl in an inert organic solvent and a triphenyl phosphine, usually aso in such a solvent, are mixed within the above proportions, The phosphine is most desirably triphenyl phosphine but otherphenyl phosphines may be used, as those with alkylphenyl groups or cther neutrally substituted phenyl groups. In place of triphenylphosphine there may be used triphenyl arsine.

When the two reactants, nickel carbonyl andthe triphenyl phosphine, are mixed, carbon monoxide is slowly evoved and a compound is formed which corresponds to. the formula Ni(CO)4-r.(MAl3)x, where M is an element of group V-B of the Periodic Table having an atomic weight from 31 to '75, Ar is a phenyl group, and :c has a value of one to two.

The catalyst is best used in the-solution in which it is prepared. The amount of catalyst required is smal varying from 0.25% to 7.5% of the weight of the methylbutynol or isopropenylacetylene.

When the trimerization reaction has been carried on for sufiicient time to ensure good conversion, any solid material present is separated by filtration or allowed to settle, and the solution decanted off. At this stage, if so desired, the re action mixture may be treated with a decolorizing aid, such as a charcoal. The trimer may be separated after distilling off solvent. When methylbutynol is trimerized, a trihydric alcohol is formed which can be crystallized out. This alcohol may also be distiled under reduced pressure, as may likewise tris(isopropenyl)benzene. Unreacted methylbutynol or isopropenylacetylene is recovered.

Tris(1 methyl 1 hydroxyethyl) benzene is readily dehydra ed by heating it at to C. with a dehydrating catalyst and removing water. The heating is usual y done in the presence of a solvent, such as benzene or toluene, which permits azeotropic distillation and separation of water. As catalyst there may be used an acid catalyst particularly for liquid phase dehydration, including dehydration in the presence of a solvent. Typical acid cata ysts include the alkali metal acid sulfates, acidic clays, cation exchange resins in their hydrogen form, such as sulfited phenol-formaldehyde condensates, sulfonated phenol-formaldehyde resins, and su fonated styrene copolymers, sulfonic acids such as benzene sulfonic acid or p-toluene sulfonic acid, sulfuric acid, hydrobromic acid, hydriodic acid. phosphoric acid, oxalic acid, and the like. Iodine acts like the acid catalysts and for convenience may be considered with them. It is quite effective in promoting the dehydration of tris(lmethyl-l-hydroxyethyl)benzene or of 3-methyl- 1-butyn3-ol to hydrocarbons. 7

After the hydroxy compound has been dehydrated in the presence of an acid catalyst, the reaction mixture is washed with water and/or an alkaline solution, such as a sodium carbonate or bicarbonate solution. It is then dried and dis tilled.

Dehydration may also be accompl shed in vapor phase. In this case tris(1-methyl-1- hydroxyethyhbenzene or 3-mehyl-l-butyn-3-ol is vaporized and passed over a dehydrating catalyst at about to about 300 C. The vapors are condensed and further purified as desired. Suitable catalysts include activated alumina, zinc oxide, activated clays, pumice impregnated with acidic materials such as phosphoric acid or dihydrogen phosphates, acidic silica gels, and the like.

The trihydric alcohol is vaporized and dehydrated at reduced pressure. The methylbutynol can be used at ordinary pressures. Since the isopropenyacetylene formed therefrom boils at a relatively low temperature. the vapors from the catalyst are passed through a trap which is suitably chilled. as with a dry ice-acetone -mixwhich methylbutynol is first dehydrated to iso- Example 2 The trimerization procedure of Example 1 was followed with 330 parts of methylbutynol, 3 parts of Ni(CO) 2.[(CsHs)aP]a, and 80 parts of benzene. The pot temperature was 86 C. during the heating. The yield of trihydric alcohol was 60%. There was recovered about 50 parts oi methylbutynol.

The trimer was dehydrated by the procedure described above except that benzene was used as a solvent. The dehydration reaction was inpropenylace ylene. The trihydric alcohol is more readil handled than isopropenylacetylene. A The trihydric cyclic alcohol formed by trimerization can be separated from the reaction mixture by crystallization.

The following examples are illustrative of methods for producing tris(isopropenyl) benzene.

Example 1 A mixture of 88 parts by weight of potassium hydroxide of 85% purity and 174 par s 01' dibutyl acetal was stirred, heated to 150 0.. and then cooled to C. Acetylene under a pressure of 13 cm. of mercury was passed into the mixture which was cooled to C. Over a period of one half hour 28 parts of acetone was added thereto. The mixture was kept at -10 to 0'' C. for two hours and stirred whi e the acetylene pressure was maintained. The mixture was brought to 25 C. and stirred at this temperature for an hour. It was then poured onto 100 parts of crushed ice. The resulting organic layer was collected, saturated with carbon dioxide, and iractiouallv distilled through a packed column. The 3-metlrv -1-buty'n-3-ol was collected between about 100 C. and 120 C. in a-yield 01' 81%. There were mixed 168 parts by weight of methyibutynol, 2 parts of catalyst,

and 400 parts of benzene. The mixture was heated under reflux for 8 hours, the pot temperature being 83 C. It was treated with 10 parts of activated charcoal and filtered hot. The illtrate was partly distilled. It was then cooled and crystals were separated. This product was recrystallized from benzene and then melted at '7 Unreacted methylbutynol was recovered by distillation of the filtrate.

A mixture of 115 parts of tris(1-methyl-1- hydroxyethyhbsnzene, 7.5 parts of sodium bisulfate, 5.7 parts of p-naphthol, and 270 parts of toluene was heated in a vessel having a packed reflux column topped with a water separator. After three hours 89% of the theoretical amount of water had been collected and heating was discontinued. The mixture was cooled and washed with water, with a 1% potassium carbonate solution. and again with water. It was dried over magnesium sulfate and distilled. The desired product was obtained in the fraction taken between 90 and 150 C. at 1.5 mm. pressure. The yield was 64%. The product wasidentifled as tris(isopropenyl-) benzene, chiefly as the 1.3.5- iorm with some of the 1.2.4-iorm present.

terruptcd when 42% ot the theoretical quantity of water hadbeen removed. The product was collected at 110-120 C./0.5 mm. in a yield of 34%, based on the starting material.

Example 3 The procedure of Example 1 was followed except that in place or the sodium bisulfate there was used 2 parts of iodine. After 63% a the theoretical water had been taken oil. the dehydration reaction was interrupted and the desired tris(isopropenyl)benzene separated at 1l0-150 C./1 mm. ina 57% yield.

In place of sodium bisuliate there may be used other non-volatile acidic agents to promote dehydration, including zinc chloride, p-toluene sulionic acid, sulionated phenol-formaldehyde resin in its hydrogen form. aluminum sulfate, or the like. These same catalysts are useful for the dehydrating oi methylbutynoi to isoproperrvlacetylene.

Example 4 Methylbutynol was heated with toluene in the presence of sodium bisuliate. Isopropenylacetylenc was collected at 8446 C.

A mixture of 18 parts 01 isopropenylacetylene, 1 part of Ni(CO)2.[(CsHs)3P]:, and parts of petroleum ether. boiling at 60-70 C., was heated under reflux for three hours. An exothermic reaction occurred early in the heating period, which carried the pot temperature to 66 C. at the end of one hour and fifteen minutes. Re-

oi three hours the temperature of the mixture was 71 C. The mixture was cooled and filtered. The filtrate was treated with one part of B- naphthol and distilled. At 1l0-150 C./1 mm.

- the traction obtained was trisisopropanylbenzene,

having a refractive index, a of 1.5671.

Repetition of the above procedure with substitution of Ni(CO) $.CIH5P for the above nickel catalyst lead to the same end result. In the same way Ni(CO)s.CsHsP may be used to promote trimerization of methylbutynol with satisfactory results. With Ni(CO)2.[CeHs):AS]2 yields are somewhat less than when the catalysts containing triphenyl phosphine are used, but the product obtained is nevertheless the trimer irom either methylbutynol or isopropenylacetylene.

Tris(isopropenyl) benzene is an interesting new hydrocarbon which is useful as a chemical intermediate. It is also valuable as a cross-linkin agent, having the desirable property's! being fairly stable under ordinary conditions and yet being active when used with readily polymerizable materials. such as styrene, vinyl esters, or acrylic acids. or mixtures of polymerizabie vinylidene compounds.

Example 5 Tris(1-methyl 1 hydroxyethyl) benzene was prepared as in Example 1. There were then mixed 84 parts by weight of it and two parts oi hosphoric acid. The mixture was heated at 110-115 C. with the pressur being reduced to two millimeters. Water was collected in a chilled trap. After parts of water was collected, the reaction mixture wa washed with a 5% sodium bicarbonate solution and with water. It was dried over soluble anhydrite and ustilled. The fraction collected at 100-130 C./1-2 mm. was tris(1- methyl-l-hydroxyethyl)benzene in 55% yield.

Example 6 Example 7 In an apparatus comprising a. flask connected to a heated tube containing activated alumina which in turn was connected to a receiver cooled with dry ice there was placed 84 parts by weight of 3-methyl-1-butyn-3-ol. The tube was heated to 250 C. The flask was heated to maintain a gentle rate of boiling of the alcohol therein. The product was collected and some of it was redistilled at 34-36 C. The distillate was quite pure isopropenylacetylene, having a refractive index, 12 of 1.4160. It should be remarked that it is not necessary to redisfiill the initial product, as it may be used directly for trimerizing. Distillation of the resulting tris(isopropenyl) benzene gives a final product of excellent purity.

Example 8 There were mixed 22 parts oi the above distilled isopropenylacetylene, 1 part of the catalyst Ni(CO) 2.[(C6H5):P]2, and parts of benzene. The mixture was heated under reflux with the temperature finally carried to 80 C. The reaction mixture was left standing until cool. The liquid was decanted from a small amount of slude. It was treated with two parts of hydroquinone and distilled. The fraction collected at l10-150 C./1 mm. was identified as tris(isopropenyl) benzene.

Repetition of the above procedure with the isopropenylacetylene as obtained from vapor phase dehydration led to the same product in similar yield.

We claim:

1. The process of preparing 1,3,5-trisisopropenylbenzene which comprises trimerizing 3-methyl- 1-butyn-3-ol by heating it in the presence of a catalyst of the formula Ni(CO)4-x.[(C6H5)3P]1:

wherein a: is a number from one to two and dehydrating the resulting trimer by heating it in the presence of a dehydrating catalyst.

2. The process of preparing 1,3,5-trisisopro- 'penylbenzene which comprises trimerizing 3- methyl-l-butyn-B-ol by heating it at 40 to C. in the presence of a catalyst of the formula Ni(CO)4.[(CeH5)aP] wherein a: is a number from one to two, whereby tris(1-methyl-1-hydroxyethyl)benzene is formed, and dehydrating said product by heating it at 80-120 C. in the presence of an acid catalyst.

3. The process of preparing 1,3,5-trisisopropenylbenzene from 3-methyl-1-butyn-3-ol which comprises the steps of dehydrating by heating at 80-120 C. in the presence of an acid catalyst and of trimerizing by heating at 40 to 120 C. in the presence of a catalyst of the formula Ni(CO)4-=.[(CsH5)aPl= wherein a: is a number from one to two.

4. As a new chemical substance, 1,3,5-'-trisisopropenylbenzene.

CHARLES H. McKEEVER. JOHN O. VAN HOOK.

No references cited.

Disclaimer 2,542,55L-0karles H. MeKeever, Glenside, and Joli n, 0. Van H0070, Roslyn,

Pa. 1,3,5-TRIs (ISOPROPENYL) BENZENE. Patent dated Feb. 20, 1951.

Disclaimer filed July 19, 1951, by the assignee, Rokm cfi Haas C'ompany.

Hereby enters this disclaimer to claim 4 of said patent.

[Ofiicial Gazette September 4, 1951.] 

3. THE PROCESS OF PREPARING 1,2,5-TRISISOPROPENYLBENZENE FROM 3-METHYL-1-BUTYN-3-OL WHICH COMPRISES THE STEPS OF DEHYDRATING BY HEATING AT 80*-120* C. IN THE PRESENCE OF AN ACID CATALYST AND OF TRIMERIZING BY HEATING AT 40* TO 120* C. IN THE PRESENCE OF A CATALYST OF THE FORMULA NI(CO)4-X.((C6H5)3P)X WHEREIN X IS A NUMBER FROM ONE TO TWO. 